Detection of specific antibodies to severe acute respiratory syndrome (SARS) coronavirus nucleocapsid protein for serodiagnosis of SARS coronavirus pneumonia.

Woo, Patrick C Y; Lau, Susanna K P; Wong, Beatrice H L; Tsoi, Hoi-wah; Fung, Ami M Y; Chan, Kwok-hung; Tam, Victoria K P; Peiris, J S Malik; Yuen, Kwok-yung

We report the evaluation of recombinant severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) nucleocapsid protein enzyme-linked immunosorbent assay (ELISA)-based antibody tests for serodiagnosis of SARS-CoV pneumonia and compare the sensitivities and specificities of this ELISA for detection of immunoglobulin G (IgG), IgM, IgA, and their combinations with serum samples from 149 healthy blood donors who donated blood 3 years ago as controls and 106 SARS-CoV pneumonia patients in Hong Kong. The specificities of the ELISA for IgG, IgM, and IgA detection were 95.3, 96.6, and 96.6%, respectively, with corresponding sensitivities of 94.3, 59.4, and 60.4%, respectively. The present ELISA appears to be a sensitive test for serodiagnosis of SARS-CoV pneumonia, is much more economical and less labor-intensive than the indirect immunofluorescence assay, and does not require cultivation of SARS-CoV.